In 2019, Andrews and Newman [‘Partitions and the minimal excludant’, Ann. Comb.23(2) (2019), 249–254] introduced the arithmetic function
$\sigma \textrm {mex}(n)$
, which denotes the sum of minimal excludants over all the partitions of n. Baruah et al. [‘A refinement of a result of Andrews and Newman on the sum of minimal excludants’, Ramanujan J., to appear] showed that the sum of minimal excludants over all the partitions of n is the same as the number of partition pairs of n into distinct parts. They proved three congruences modulo
$4$
and
$8$
for two functions appearing in this refinement and conjectured two further congruences modulo
$8$
and
$16$
. We confirm these two conjectures by using q-series manipulations and modular forms.